Vitali is a 6'8 SuperHeavyweight who out weighted his opponent by 35+ Pounds, his opponent was a former MiddleWeight and seriously lacked any sort of punching power. Vitali was also winning on the cards.

That being said: Here is a few key points.

Chris Byrd starting in the middle rounds was actually clowning Vitali and forcing him to miss 90% of his punches. Byrd was also landing at a much higher rate and was visibly hurting Vitali as he got Vitali going backwards from that point on out. After the fight, Vitali himself admits that he 'was not sure if he was winning the fight'.
I feel that Byrd's pressure and defensive abilities were frustrating Vitali and he was actually in a much closer fight than some people initially realized.

After the fight, Vitali's home crowd booed him and it was sad. Vitali also pretended he didn't speak English when Larry Merchant was dominating him in the interview. That's understandable since it's the first time in history a champion quit against some one 9 inches shorter.

Victor Ortiz had his jaw noticeably broken. I think one more hit would have damaged him for life.

Vitali's 'shoulder pain' is just words. There is really no evidence that he was 'hurt' because of it. He probably just quit due to lack of heart.

Everyone will probably shiiit on Ortiz because his fight was more recent and a lot of these guys didn't even see the Vitali fight. The simple fact is, Ortiz was going to get stopped anyway. Vitali was winning the fight and all he had to do was use his reach, his other hand, take the pain, and he probably would have won the fight. Tyrel Biggs fought Jeff Sims with a broken collar bone and just used his left hand for the rest of the fight and won. It seemed like Vitali didn't even try.

Ortiz quit VS Mayweather with a fake kiss, hug and headbutt.
Don't even get me started on I am too young to be hurt like this VS Maidana.

I don't blame him for quitting against Maidana. Boxing fans act like they've never seen two fighters beat the prime out of one another. The end of the day the proof is in the pudding, he quit against Maidana and was able to secure handsome pay checks against Peterson, Berto and Mayweather. He also came close to scooping a big fight with Canelo.